Tough time with pregnancy after miscarriage

I had a miscarriage on Christmas 2015 and am currently 11w5d with my rainbow baby. I am having a really hard time adjusting. I am excited about this baby and I feel incredibly blessed to have been able to conceive again so quickly....but I can't help thinking about the baby I lost. Every milestone with this baby reminds me that I will never get to experience those things with my first baby. I feel so guilty for not being able to truly enjoy being pregnant again, because I don't take it for granted. I made a memory box for the baby I lost and all I can think is that all I have left of that baby is a box of things....has anyone else struggled like this? Just really want to pull myself out of this depression but I can't seem to do it....